Notice to Richard P. Speck - I said spacecraft, not spacesuit with added heat shield

If we can get the cost of launching cargo down to $100/kg, and have a decent space infrastructure (craft already there, fuel depots using fuel from Luna/Asteroids), then ultralight spacecraft are the final piece in the puzzle. If they weigh 200kg/passenger (passenger included) then that would come to $20,000/person. If the rest of the flight (to the other planet) costs an extra $5000, then the totals $25,000. I'm sure people spend more than this in moving countries.

you're starting to violate physical laws once you try to get your spacecraft that small. pretty much you're required to have something propelled by electricity and have that electricity delivered to you while in "flight". the only thing actually capable of having this is a space elevator lifter platform as far as i'm aware. even then, you're not gonna get 200kg/passenger. it's just way too hard what with life support and all that.

ok if you're not counting booster rockets as part of the craft then you're not making an ultralight craft. rockets are expensive, and so is fuel for the rockets. if you want to use conventional chemical propulsion you will never get under $100/lb because your propellant cost will always be higher than that.

i don't have time to calculate a delta v cost per kg per km/s using just propellant costs but it's not going to be under $100 for any reasonable delta v even using best case estimates. sure you can have a metal shell with some air scrubbers and circulation equipment and sit up in LEO and it'll be not too expensive to operate, but once you start considering how you're gonna get down, what you want to do when you're up there, if you want to change orbits at all, you lose the ability to have a cheap craft. and while yes, the part that flies around in space is the "spacecraft", it's also ignoring the issue if you don't include the cost of getting the craft to space as part of the "spacecraft" cost.